Pid Controller - WEG CFW100 Programming Manual

14 APPLICATIONS
Using the SoftPLC function of the inverter, it is possible to develop an application (or functionality) in ladder language
and include it in the inverter software.
Parameter P903 allows selecting the application and uploading it to the SoftPLC execution area of the inverter.
The frequency inverter has the following application already implanted:

PID Controller.

14.1 PID CONTROLLER
The PID controller application can be used to control a process in closed loop. This application adds a proportional,
integral and derivative controller superimposed to the regular speed control of the frequency inverter having selection
options:
Control setpoint source.
Process variable source.
Operation mode in manual or automatic mode.
Alarms by low or high process variable level.
Configuration of the control action in direct or reverse mode.
Setting the conditions to activate the sleep and wake up mode.
Basically, the PID controller application compares the control setpoint to the process variable and controls the
motor speed to try to eliminate any errors so as to keep the process variable equal to the control setpoint required
by the user. The setting of the gains P, I and D determine the speed at which the inverter will respond to eliminate
that error. See the PID controller block diagram below
Control
setpoint
AI1
AI2
P911
P912
P913
P914
P915
Selection via
P920
Process variable
AI1
AI2
AI1 - AI2
Selection
P922, P923
via P921
Application examples of the PID controller:
Flow or pressure control in a pipe system.
Temperature of a furnace or oven.
Dosing of chemicals in tanks.
Filter for control
Control
setpoint
action via
P911
P935
P916
Figure 14.1: PID controller block diagram
PID
controller
P928
P917
P931, P932
P933, P934
APPLICATIONS
Operation
mode via
P929
Speed
reference
0,0 % (P133) a
100,0 % (P134)
P918
Micro Mini Drives | 14-1
14